Physicochemical characterization of ten blackcurrant (Ribes nigrum) cultivars, their bioactivity related to type 2 diabetes and inflammation, and chemical changes after lactic acid fermentation
Blackcurrants (Ribes nigrum) are small, astringent berries that are not well known in the United States due to being banned for almost a century from the spread of a fungus that threatened the timber industry. However, new fungus resistant cultivars of blackcurrants have been created, and the high amounts of bioactive compounds, vitamins, minerals, and antioxidants in the currants, have started to create growing interest in developing the U.S. blackcurrant industry. Fermentation of berry juice is a possible way to create a blackcurrant product with a longer shelf life, enhanced bioactive compounds and antioxidants, and an improved sensory experience. The objective of this research was to characterize ten blackcurrant varieties and their juices, including analyzing their effect on inhibition of markers of type two diabetes and inflammation. In addition, evaluate the impact of lactobacilli fermentation of blackcurrant juice on phenolic compounds and antioxidant capacity. Blackcurrant cultivars (Ben Lomond, Blackcomb, Cheakamus, Consort, Coronet, Nicola, Stikine, Titania, Tiben, and Whistler) were juiced and analyzed physically and chemically. The mass, length, width, percent skins and seeds, and the juice yield were measured for the whole berries. The juice was analyzed by density, pH, BRIX, total acidity, viscosity, and color. For phenolic analysis, total polyphenols (TP), total anthocyanins (TA), total condensed tannins (TT), and quantification of the four major anthocyanins were completed. Antioxidant capacity and inhibition of markers of type two diabetes and inflammation were also analyzed, which included dipeptidyl peptidase-IV, α-amylase, α-glucosidase, nitric oxide synthase, and cyclooxygenase-2. Seven strains of lactic acid bacteria were analyzed of tannase and ß-glucosidase activity. The cultivar Blackcomb was chosen along with four strains of lactic acid bacteria (L. plantarum A, L. paracasei B, L. rhamnosus C, and L. plantarum D) to ferment the blackcurrant juice. The phenolic composition and antioxidant capacity were analyzed over the fermentation. Results showed that for each fruit, the mass ranged from 0.47-1.22 g and the diameter ranged from 7.42-14.42 mm. For juices, the pH ranged from 2.80-2.96, soluble solids from 11.33-17.5%, total acidity from 3.17-4.26 g/100 mL, and viscosity from 1.28-273.83 mPa•s. Total anthocyanins ranged from 1.81-5.48 mg eq cyanidin 3-O-glucoside/100 g, total polyphenols from 7.67-39.70 mg eq gallic acid/100 g, total condensed tannins from 3.24-7.76 g eq catechin/100 g, and antioxidant capacity from 219.24-499.26 μmol eq Trolox/100 g. Coronet and Consort juices contained the highest TA, TP, and antioxidants. Whistler contained high concentrations of the major anthocyaniins. Juices from all cultivars favorably inhibited enzyme activities used as surrogate biochemical markers for type 2 diabetes and inflammation. For the fermentation, ß-glucosidase and tannase enzymes were present in all bacteria strains tested. After fermentation, TA decreased but had no significant change compared to the control, and TT decreased significantly from the control (after 24 h, 182.24-264.48% decrease). There was a significant increase in antioxidant capacity for Lactiplantibacillus plantarum strains (after 24 h, 501.68% and 444.47% increase for A and D, respectively) and in TP for Lacticaseibacillus paracasei B (after 24 h, a 93.65% increase) compared to the control. L. paracasei B had a clear effect on the increase of all phenolic acids measured (protocatechuic acid, p-coumaric acid, gallic acid, ferulic acid, and caffeic acid). In conclusion, Consort and Coronet cultivars are the best cultivars to choose for bioactive properties, inhibition of markers of type 2 diabetes and inflammation, and ease of handling. In addition, L. plantarum A or L. paracasei B are the most promising strains for increased benefits after fermentation.
β-glucosidase, Blackcurrants, Inflammation, Lactic acid fermentation, Phenolic compounds, Ribes nigrum, Tannase, Type 2 diabetes
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign